small change to last fix, to get xml:base right

* catalog.c: small change to last fix, to get xml:base right
diff --git a/catalog.c b/catalog.c
index 908dda5..c01c584 100644
--- a/catalog.c
+++ b/catalog.c
@@ -550,8 +550,13 @@
 		case XML_CATA_GROUP:
 		    node = xmlNewDocNode(doc, ns, BAD_CAST "group", NULL);
 		    xmlSetProp(node, BAD_CAST "id", cur->name);
-		    if (cur->value != NULL)
-			xmlSetProp(node, BAD_CAST "uri", cur->value);
+		    if (cur->value != NULL) {
+		        xmlNsPtr xns;
+			xns = xmlSearchNsByHref(doc, node, XML_XML_NAMESPACE);
+			if (xns != NULL)
+			    xmlSetNsProp(node, xns, BAD_CAST "base",
+			    		 cur->value);
+		    }
 		    switch (cur->prefer) {
 			case XML_CATA_PREFER_NONE:
 		            break;